docs: def write_float_matrices(scp_path, ark_path, matrices):
          """ Write the given dict matrices (utt-id/float ndarray) to the given scp and ark files. """
  
          scp_entries = []
  
          with open(ark_path, 'wb') as f:
              for utterance_id in sorted(list(matrices.keys())):
                  matrix = matrices[utterance_id]
  
                  assert (matrix.dtype == np.float32)
  
                  f.write(('{} '.format(utterance_id)).encode('utf-8'))
  
                  offset = f.tell()
  
                  f.write(b'\x00B')
                  f.write(b'FM ')
                  f.write(b'\x04')
                  f.write(struct.pack('<i', np.size(matrix, 0)))
                  f.write(b'\x04')
                  f.write(struct.pack('<i', np.size(matrix, 1)))
  
                  flattened = matrix.reshape(np.size(matrix, 0) * np.size(matrix, 1))
                  flattened.tofile(f, sep='')
  
                  scp_entries.append('{} {}:{}'.format(utterance_id, ark_path, offset))
  
          with open(scp_path, 'w') as f:
              f.write('\n'.join(scp_entries))